Democrats are showing signs of life after November’s shocking election losses. They are energized and turning out in large numbers for marches and town halls. Their chief adversary, Donald Trump, has record-low approval ratings for a new president and is prone to self-inflicted wounds.

Yet, as they convene in Atlanta to select a new party chair this weekend, the Democrats should resist the temptation to let their far left wing control too much and to assume that indignation alone can win elections.

The first few weeks of the Trump administration reinforce a key point that Hillary Clinton failed to drive home: Many of Trump’s policies will not help many of the people who voted for him.

The most prominent example of this is Trump’s plan to repeal Obamacare, which allowed 20 million people to get health coverage, and replace it with a to-be-determined “something terrific.” Recent polls suggest the Republicans’ repeal-and-replace message isn’t nearly as popular as they might think.

Beyond defending the Affordable Care Act, Democrats also have a chance to press a message of economic fairness on taxes. Like the Obamacare repeal, the Republicans’ tax reform plan would send money flowing away from Americans of modest means and back toward the rich.

Trump and House Republicans have proposed raising the lowest tax bracket (from 10% to 12% for individuals with annual taxable income less than $9,325) while reducing the top bracket (from 39.6% to 33% for those making more than $418,400). They also want to remove all taxes on inherited wealth.

It ought to be easy for Democrats to point out the hypocrisy of Republican populism and provide an alternative vision, one that should help them appeal to some of the white working-class voters who deserted them in 2016.

Nor is it hard to imagine a backlash against Trump immigration and refugee policies that harm families and otherwise sympathetic neighbors, colleagues, friends and relatives.

What Democrats should not do is write off Middle America and become the party of coastal elites and unarticulated rage. The “not my president” theme of marches on Presidents Day strikes the wrong chord. So does reflexive opposition to everything Trump does.

There is, to be sure, something to be gained from stern resistance to Trump, especially going into a midterm election cycle. Just as the Republicans’ scorched-earth tactics helped them to major wins in 2010 and again in 2014, Democrats could rack up gains in 2018 and beyond simply by being the alternative to an unpopular president.

At the same time, Democrats need to be more than a resistance movement. They need younger leadership, policies that appeal to moderates and independents, voters who actually turn out, and a compelling and coherent vision for how they’d be different from Trump. Above all, they need to follow their principles where they lead — in support of Trump in some cases, likely in opposition in many more.

Much will be made of who wins the party chairmanship, and how much the new leader is associated with establishment or insurgent camps. But the vast majority of the important decisions will be made by officeholders, candidates and activist groups far from Democratic National Committee headquarters.

Democrats have at their disposal some strong arguments with broad appeal. They should make them.